大乘起信論廣釋卷第三．四．五 3.75

3.75

論。何以故至唯佛能知　釋曰。此釋深所以義也。緣起妙理貫通凡聖唯佛窮了。何以故耶。下答文中有其三節。初明即淨而常染。是心本來自性淨者。謂即本覺緣起真心據本而言。自體無染非別淨法可令淨。故此即總顯緣起因也。而有無明者。即依心體有此無明不覺緣也。此即顯其緣起之緣。為無明染有染心者。心體為此無明所染。而淨心體有染心也。此即顯其緣起之相。總是釋經不染而染。顯有染心等者。次明即染而常淨。謂本覺心雖被所染。常有染心性自真故。而不不失本淨心性。是釋經言染而不染。唯佛窮了者。明佛能知此理既深。非餘盡了故。緣起理唯佛能知。故勝鬘云。自性清淨心難可了知。彼心為煩惱所染。亦難可了知。楞伽經云。如來藏是清淨相。客塵煩惱垢染不淨。我今與汝及諸菩薩甚深智者能了分別。今論釋此顯甚深也。

[Treatise:] Why is this? [...] only a Buddha can know. [Commentary:] This explains the meaning of why it is profound. The subtle principle of dependent origination runs through ordinary persons and sages, yet only a Buddha exhaustively understands it. Why is this? In the answer text below there are three sections. First, clarifying that while pure, it is constantly defiled: "This mind's original self-nature is pure" means that the true mind of dependent origination, which is original awakening, speaking in terms of its origin, is in its own substance undefiled; it is not that there is another pure dharma that could make it pure; this generally reveals the cause of dependent origination. "Yet there is avidyā" means that relying on the mental substance there is this condition of avidyā and non-awakening; this reveals the condition of dependent origination. "Being defiled by avidyā, there is a defiled mind" means that the mental substance is defiled by this avidyā, and on the pure mental substance there is a defiled mind; this reveals the characteristic of dependent origination. All this explains the sūtra's "undefiled yet defiled." "Revealing that there is a defiled mind," etc.: Next, clarifying that while defiled, it is constantly pure. It means that although the mind of original awakening is defiled by it, constantly having a defiled mind, its nature is inherently real, so it does not lose its fundamentally pure mental nature. This explains the sūtra's "defiled yet undefiled." "Only a Buddha can exhaustively understand" clarifies that the Buddha can know this: since this principle is so profound, it is not fully understood by others, hence the principle of dependent origination can only be known by a Buddha. Thus the Śrīmālā [Sūtra] says: "The intrinsically pure mind is difficult to understand; that that mind is defiled by afflictions is also difficult to understand." The Laṅkāvatāra Sūtra says: "The tathāgatagarbha has a pure mark, yet is defiled and impure with the stains of adventitious defilements. Now I, together with you and the bodhisattvas of profound wisdom, are able to fully understand and distinguish it." The present treatise comments on this to show its profound depth.